Personally, I find many of the themes and the plot points of WoT to be unbelievable, but I can enjoy the series because it wasn't meant to be "realistic" or "believable". It is meant to be fun.

Once I got over my need for this story to have a deeper meaning beyond engaging my imagination, I started to enjoy it for what it is. I feel that there are works of fiction, such as "War and Peace" that try to comment or reveal something about the human condition. While "Wheel of Time" certainly has themes, they apply only as far as the bounds of this fantasy series.

The fact that we have characters whom unlikely events occur around to the extent that they seem uberpowerful and lucky (t'a'veren) in the story stretches belief enough to make suspending your disbelief a non-issue. You aren't supposed to 'believe' these characters issues are real. IMHO you are supposed to have fun with the ride getting from Point A to Point B.